Study on Crown of Main Coniferous Species in Natural Secondary Forest

Abstract

2638 branch samples are gained from the 14 sample spots and the data of 50 parse trees in the spots investigated by Muling Forestry Bureau in 2008. The type of the curve are determined by the observation of the radius(r) of various kinds of trees and the scatter diagram graph of crown depth (lx) . This paper is to use power function, single formula, parabola and hyperbolic function models to fit. Through the comparison of the results of fitting, it is found that the fitting effect of the average crow of Korean pine is the best whose correlation coefficient achieves 0.58, and for parabola, spruce and fir are the best respectively with correlation coefficient 0.69 and 0.72; The same model is applied to fit the outside shape of the three species and the result is similar with that of average crown: hyperbolic function of Korean pine is the best and parabola of spruce and fir are the best. After test, it is found that forecast accuracy of model is higher. Average crown of Korean pine is 95.7% and outside crown is 92.1%; Average crown of fir is 94.9% and outside crown is ：95.9%; Average crown of Spruce is 96.0% and outside crown is 95.4%. From the point of comprehensive results, the fitting of crown shape model is better and the model chosen can better describe the crown shape of the main conifer species in Muling area, achieving the desired objectives.